Right. Air/fuel is generally close to 14:1 (by weight) although that is creeping higher in the interests of fuel economy. That's actually about 3:1 by weight of oxygen. The remainder is nitrogen, which is important for power production and combustion but does not participate in combustion. (Ideally at least; some NOx is formed invariably due to the high temperatures in the cylinder.)However as a auto technician years ago ( they called us guys motor mechanics in those days) the ratio of O2 to fuel was closer to 4:1 and certainly not 1:1
Agreed there. In addition, I would also add that for every pound of oxygen you use for combustion you get 1.4 pounds of CO2.so... it is relatively easy to extend and suggest that for every CO2 unit produced ( in the mix of gasses produced) a significant amount of O2 must be consumed. ( potentially at a rate of 4:1) Even so, on face value, that means that a relatively trivial amount of O2 has been consumed in the production of our current atmospheric CO2.
Agreed. By the same measure, though, we have much larger O2 reserves that would be suggested by the air, since a lot of O2 is dissolved in the ocean.This does not account for the CO2 that is being taken up by oceans and increased CO2 fertilization effects.
One can assume that any increase fertilization effects become net gain zero as the flora involved have to sustain their own existence with the O2 and CO2 they produce.
There fore it can be assumed that the Anthro CO2 production is significantly greater than that which is retained in the atmosphere.
Quantifying that CO2 produced and absorbed is not easy, ocean acidification ( accounts for 30-40% of anthro production), dead zones ( 405 at last count - 2008)
Summary:
Anthro CO2 production is significantly higher than the .04% indicated in the atmosphere. Which means that O2 consumption is considerably higher than that which is indicated by only atmospheric data.
"Effective" O2 is not a scientific term. Partial pressure is. So if you see someone using the term "effective O2" it's probably a science writer trying (and perhaps failing) to make the topic more understandable to laypeople.It is worth noting that the confusion between "effective O2 " and actual O2 is often demonstrated in many supposedly erudite reports when dealing with this issue indicating a degree of incompetence or deliberate obfuscation.
Switching "category" or context to reduce alarm is one possibility.
Or it was an internal measurement. With very high standards for insulation of new buildings, often air exchange is reduced. 19.7% would be somewhat unusual (because it would suggest an increase in CO2 to something like 1%, which is pretty debilitating) but possible.Also prior to the Scrips O2 program being established scientific reports from well regarded high altitude research stations ( French and Swiss) of ambient O2 being as low as 19.7% were published on the net and then rapidly removed from the web at the time indicating some sort of intervention ( or cover up) Perhaps they found their reports mistaken and removed them to prevent embarrassment. I shall never know.
Sorry, that simply makes no sense. The tiny changes you are talking about are completely dwarfed by the larger changes in a city like Denver (or even Leadville.) If such small changes would lead to increased breathing problems, anxiety, opioid use, hyperventilation etc then people would be coked to the gills and panting nonstop in Denver, never mind Leadville (at 10,000 feet.) If those 1% changes you talk about are enough to cause all those problems, then at 5% people would be hypoxic, barely able to breathe, having all sorts of serious medical problems.So to me, ( just so you know where I am coming from) when you look at the big picture you see a global population, especially in the West ( data availability), that is starting to experience increased breathing problems which forces me to the tentative conclusion that atmospheric O2 depletion causing mild hypoxemia may be, in part, responsible.
Yet they run ultramarathons in Leadville, perhaps the strongest possible evidence that people can adapt to such changes.
That is simply not proven out (or even suggested) by any medical data. Indeed, the opposite is true. While people notice rising CO2 levels very rapidly, they don't notice low O2 levels at all, often until it's too late. There have been several cases of people unknowingly working in tanks that were full of nitrogen or helium or other inert gas (i.e. 0% oxygen.) They seemed to be fine until they collapsed. As far as they could tell everything was fine - because we determine how breathable air is primarily by how much CO2 is in it, not how much O2 is in it. (The ones that could be retrieved quickly survived.)Suffice to say that we Humans are incredibly sensitive and thus responsive to "actual" O2 levels.